Unit 6 Contents

Estimating Sums and Differences

Ming and Keenya were researching the national parks in the United States. They found that Yellowstone National Park, established in 1872, was the world's first national park.

Ming organized some of the national park information they found in a table.

1. Ming estimated that there are about 1,300,000 acres of national park land in Arizona. Ming wrote this number sentence showing the convenient numbers he chose:
1,200,000 + 100,000 = 1,300,000 acres Explain how Ming arrived at his estimate.
2. Find another estimate for the amount of park land in Arizona. Write a number sentence to show how you estimated.